Venous thromboembolism

24 Venous thromboembolism




Overview/pathophysiology


Venous thromboembolism (VTE) describes the conditions of deep vein thrombophlebitis (DVT) and pulmonary embolism. The development of VTE is associated with various etiologies and risk factors. Any predisposing condition that affects coagulation or stasis of the blood can contribute to VTE. Hemoconcentration, vessel trauma or inflammation, hypercoagulability, and immobility are the most common risk factors for VTE.


Hemoconcentration is caused by dehydration, including inadequate fluid resuscitation in the perioperative period. Vessel trauma or inflammation may result from chemical irritation caused by intravenous (IV) solutions, direct trauma, including venipuncture, and improper prolonged positioning. Hypercoagulability is often due to malignancies, hereditary factors, or estrogen therapy.


Immobility resulting from prolonged bedrest or operating room table positioning contributes to venous stasis. Additionally, venous stasis may occur with chronic heart failure, shock states, structural disorders of the veins, and following abdominal, pelvic, or orthopedic operative procedures.


DVT describes thrombosis and inflammation in the deep venous system, most commonly of the lower extremities. The most serious complication of DVT is embolization, causing a pulmonary embolus (PE).



Health care setting


Acute care or primary care, often following prolonged or complicated hospitalization



Assessment




Signs and symptoms:


Assessments may be divided into those in the area of the thrombus (associated with inflammation) and those distal to the clot (associated with venous congestion). Over the site of the thrombus, signs and symptoms can include pain, tenderness, erythema, local warmth, and increased limb circumference. Distal to the area of thrombus, the extremity may be cool, pale or cyanotic, and edematous and will display prominent superficial veins. Additional findings include unilateral leg swelling, fever, and tachycardia. Sometimes the condition is clinically “silent,” and the late presenting sign may be a PE. (See “Pulmonary Embolus,” p. 125.)



Physical assessment:


A knot or bump occasionally can be felt on palpation. If the patient is asymptomatic for DVT, pain elicited with foot dorsiflexion (Homans’ sign) may be a sign of DVT, but clinical suspicion often guides further diagnostic workup.



Risk factors:


Prolonged bedrest and immobility, leg trauma, recent surgery, malignancy, estrogen therapy, hypercoagulability, obesity, varicose veins.



Diagnostic tests




Doppler ultrasound:


Identifies changes in blood flow secondary to presence of a thrombus. Doppler venous sounds are similar to that of wind blowing and are respirophasic (wax and wane with patient’s inspiration).



Duplex imaging:


Use of ultrasound to assess veins for changes in flow and increased velocities when a clot is obstructing flow. Accuracy and sensitivity are good diagnostic measures for DVT.



Impedance plethysmography:


Estimates blood flow using measures of resistance and normal changes that occur during pulsatile blood flow. It is highly accurate above the knee.



Plasma markers (D-dimer test):


A positive plasma D-dimer test is indicative of fibrin breakdown, and further evaluation is warranted. A negative D-dimer test is helpful in excluding DVT if noninvasive testing also is negative.





Nursing diagnoses:


Ineffective peripheral tissue perfusion


Risk for decreased cardiac perfusion

related to thrombus formation or embolization


Desired Outcome: Following emergency interventions, patient has adequate peripheral and cardiac perfusion as evidenced by normal extremity color, temperature, and sensation; respiratory rate (RR) 12-20 breaths/min with normal depth and pattern (eupnea); heart rate (HR) 100 bpm or less; blood pressure (BP) within 20 mm Hg of baseline BP; O2 saturation greater than 92%; and normal breath sounds.
















ASSESSMENT/INTERVENTIONS RATIONALES
Assess for lower extremity pain, erythema, increased limb girth, local warmth, distal pale skin, edema, and venous dilation. If indicators appear, maintain patient on bedrest and notify health care provider promptly. These are early indicators of peripheral thrombus formation (DVT), which necessitate bedrest and prompt medical attention to prevent embolization.
Assess for and immediately report sudden onset of chest pain, dyspnea, tachypnea, tachycardia, hypotension, hemoptysis, shallow respirations, crackles (rales), O2 saturation 92% or less, decreased breath sounds, and diaphoresis. These are signs of PE, a life-threatening situation. If they occur, prompt medical attention is crucial.
Administer anticoagulants as prescribed.
Anticoagulants prevent propagation of a clot. Heparin is used during the acute phase, and long-term warfarin therapy is used after the acute phase. Six months of anticoagulation is recommended for a first occurrence of DVT. Low-molecular-weight heparin may be prescribed, enabling outpatient management of DVT until warfarin levels are therapeutic.
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Jul 18, 2016 | Posted by in NURSING | Comments Off on Venous thromboembolism

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